Hiroshima J. Med. Sci. Vol.42, No.3, 125~ 128, September, 1993 HIJM 42-17

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A Case Report of Epithelioid Leiomyosarcoma of Transverse Mesocolon: diagnosis and treatment

Kazuhiro KOCHI1), Shigenori SHIGEMOT01\ Motoaki ISON01\ Reiko MAEDA2),

Yasuo MAEDA2), Miho SHIGEMOT02\ Wataru YASUI3) and Yuichiro MATSUURA4)

1) The Department of Surgery, 2) The Department of Internal Medicine, Togouchi National Health Insurance Hospital, Hiroshima, Japan

3) The First Department of, Pathology, Hiroshima University School of Medicine, Hiroshima, Japan 4) The First Department of Surgery, Hiroshima University School of Medicine, Hiroshima, Japan

ABSTRACT A case of epithelioid leiomyosarcoma of the transverse mesocolon in a 45-year-old man was

reported. The patient had a rapidly growing mass in the left upper quadrant. Ultrasonogra­phy, gastrointestinography, and abdominal computed tomography showed that the mass was separated from the pancreas, the gastrointestinal tract, and the retroperitoneal organs. Preop­eratively the primary origin of this tumor was related to the transverse mesocolon. On laparo­tomy the tumor of 5cm by 6cm by 3cm in size was found in the anterior lief of the transverse mesocolon and the mass was resected entirely. The patient is well 18 months after surgical treatment with no evidence of recurrence.

Key words: Epithelioid leiomyosarcoma of transverse mesocolon, Diagnosis, Treatment

Malignant smooth muscle tumors of the trans­verse mesocolon is a rare condition. Only 10 cases have been reported since 1965 in Japan l). A five­year survival rate has been reported of 0-20%2,3).

Complete excision affords the only real hope of long-term salvage. We report a case in which en bloc resection was possible, and discuss diagnosis and treatment.

CASE REPORT 45-year-old man was admitted to our hospital

with an upper abdominal mass. He had no com­plaints other than a rapidly growing mass. Physi­cal examination revealed a firm and smooth mass, 5 cm by 6 cm in size, located at the left upper quadrant of the abdomen. Laboratory in­vestigations showed no abnormalities, and the values of CEA and CA19-9 were within normal limits.

Abdominal ultrasonography showed a mass of 6 cm by 7 cm in size, located above the pancreas which showed the "pseudo kidney sign", that is, hyperechoic area at the periphery and and a hy­poechoic area at the center (Fig. 1-a). Space occu­pying lesion of the liver and swelling lymphnodes around the aorta were not recognized.

Upper gastrointestinography showed the com­pression of the stomach and transverse colon to-

ward superior by the mass. Ba enema showed no mucosa! and extra colonic lesion.

Computed tomography showed that the mass was separated from the transverse colon and that it had not invaded to the pancreas. There was no evidence of the invasion to the pancreas and oth­er retroperitoneal organs, or of metastasis to the lymphnodes and liver (Fig. 1-b).

Celiac- and supramesenteric-arteriography showed an irregular tumor stain and revealed that the feeding artery of this tumor was the midcolic artery (Fig. 1-c). Thus, our diagnosis was of a primary tumor of the transverse mesoco­lon.

A laparotomy was performed on March 3rd, 1991. The tumor was 5 cm by 6 cm in size and arose from the anterior sheath of the transverse mesocolon. Invasion to the pancreas was not clear, and adhesion to the posterior sheath of the transverse mesocolon was not severe so that the bursectomy was easily performed. Obvious metas­tasis to the lymphnodes and other organs was not recognized except for inflammatory lymphadeno­pathy of the bursa omentalis (Fig. 2-a).

Macroscopically the tumor was 5 cm by 6cm by 3 cm in size and a well-capsuled solid tumor con­taining cystic necrosis (Fig. 2-b).

Microscopically, the tumor was composed of-

Reprint requests to: Kazuhiro Kochi, The Department of Surgery, Togouchi National Health Insurance Hospital, 800-1 Togouchi-cho, Yamagata-gun, Hiroshima 731-38, Japan.

126 K. Kochi et al

Fig. 1-a. Abdominal ultrasonography showed a mass of 6 cm by 7cm in size, located above the pan­creas. Fig. 1-b. Computed tomography showed the mass was separated from the transverse colon, pancreas, and retroperitoneal organs. Fig. 1-c. Supramesenteric arteriography showed an irregular tumor stain and revealed that the feeding artery was the midcolic artery (arrow).

Fig. 2-a. On laparotomy, the tumor was located at the anterior sheath of the transverse mesocolon. Fig. 2-b. Macroscopically the tumor was 5 cm by 6 cm by 3 cm in size, and was solid with cystic necrosis.

Epithelioid Leiomyosarcoma of Transverse Mesocolon 127

Fig. 3. Microscopic findings of the epithelioid leiomyosarcoma (HE staining). Fig. 3-a. Short spindled cells proliferate in sheets rather than fascicles. Fig. 3-b. The round or short spindled tumor cells have amphophilic cytoplasm, and a small number of multinucleated giant cells are seen. Fig.3-c. In some parts, tumor cells with clear cytoplasm and plemorphic giant cells are found. Fig.3-d. Mitotic figure is not frequent.

short spindled and rounded cells that grew in sheets rather than fascicles (Fig. 3-a). The short spindled tumor cells had amphophilic cytoplasm, and multinucleased giant cells were present (Fig. 3-b). Some epithelioid tumor cells showed clear cytoplasm, and in part cellular pleomorphism was prominent (Fig. 3-c). The cellularity varied in areas, and mitoses were not frequently found (Fig. 3-d approximately 1/10 high-power field). In some parts, myxoid degeneration and cystic change were seen. Histochemically, the cytoplasm of the tumor cells was red in Masson's trichrome staining, and there was no positive oil redo 0 staining in the tumor cells. Reticulin staining showed fine fibers around the tumor cells. Immu­nohistochemically, the short spindled tumor cells were positive for desmin but negative for S-100 protein, neuron-specific enolase, alpha-smooth muscle actin and myoglobin. The tumor was diag­nosed as epithelioid leiomyosarcoma. There was no findings of metastasis in the resected lymph-

nodes. Neither radiotherapy nor chemotherapy was ap­

plied, since the tumor had been excised complete­ly and there were no metastatic lymphnodes. The patient is alive and well 27 months after surgical treatment and there is no evidence of recurrence.

DISCUSSION Malignant smooth muscle tumors of the trans­

verse mesocolon is an uncommon disease. Only 10 cases have been reported in Japan since 19658). Epithelioid leiomyosarcoma (malignant leiomyoblastoma) is rare.

Typical pathological features of epithelioid smooth muscle tumors are that they are com­posed of nodules of short spindle and rounded epithelioid cells with a clear cytoplasm. Their morphological character is different from leiomyo­sarcoma2). Epithelioid leiomyoma is distinguished from epithelioid leiomyosarcoma principally on the basis of mitotic figures and size. More than

128 K. Kochi et al

4 or 5 mitosis/50 HPF and greater than 6 cm in size is considered malignant2).

Although accurate preoperative diagnosis for a abdominal rapidly growing mass in the abdomen is difficult preoperatively, it is possible to locate the tumor and it is important to determine its resectability. First ultrasonography is carried out in order to investigate the location and the char­acteristics of the mass, that is whether the mass comes from the pancreas or not5). As the second step upper gastrointestinography and barium en­ema predispose whether the primary origin of the mass is the digestive system or the extradigestive system. The findings of abdominal computed to­mography are useful for determining communica­tion to the retroperitoneal organs.

Angiography is helpful for showing unexpected anomalies of the celiac and mesenteric arteries. The most consistent feature of the angiography of mesenteric smooth muscle tumors is hypovascu­larity at the tumor site and displacement of ma­jor vessels by the tumor3). Tumor staining and early venous filling are not frequently seen. In the present case, celiac- and supramesenteric ar­teriography showed hypervascularity and early filling from the feeding artery, although this is not frequently seen on the literature. Because the first branch of the supramesenteric artery which communicates to the gastroepilpic artery fed the tumor, the midcolic artery was suspected to be the feeding artery. Thus, an assessment of tumor characteristics is done preoperatively by integrat­ing these findings of image studies.

The most reliable treatment is complete resec­tion of the tumor. Surgical technique should es­sentially include en bloc excision of involved organs including the tumor capsule1). Blood loss can be reduced by ligating the feeding artery in the early stage, especially when abnormal adhe­sion to other organs is involved. As far as malig­nancy of the mesocolon is concerned, the

operative procedures should involve bursectomy, which is useful not only for resecting the tumor but also for evaluating the connection to the pan­creas, stomach, and transverse colon. However many unresectable cases have been re­ported 1·4·6-8), and neither chemotherapy nor ra­diotherapy is effective for malignant tumors associated with smooth musclel,4,6-8). En bloc re­section based on the results of an early diagnosis should be made to minimize the risk of residual disease.

(Received March 29, 1993) (Accepted July 9, 1993)

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